Use the command "git clone git://URL" to create a local clone of an online repository.
You can then add your own files and file changes to it using the commands "git add" followed by "git commit".
Use "git pull" before any other operations on the repository. It will update your local copy and make sure you are always dealing with, adding and committing to the current file base. Because "git pull" helps you obtain those changes that others have committed to the repo.

"git ." (git dot) is not a known command; you may however use "git add ." (git add dot) in order to add all files in the current directory.